Reporting from Washington — The Justice Department is trying to protect its political appointees from the Fast and Furious scandal by concealing an internal "smoking gun" report and other documents that acknowledge the role top officials played in the program that allowed firearms to flow illegally into Mexico, according to the head of the Bureau of Alcohol, Tobacco, Firearms and Explosives.

Kenneth E. Melson, the ATF's acting director, also told congressional investigators this month that the affidavits prepared to obtain wiretaps used in the ill-fated operation were inconsistent with Justice Department officials' public statements about the program. Justice Department officials advised him not to raise his concerns with Congress about "institutional problems" with the Fast and Furious operation, Melson said.

"It was very frustrating to all of us," Melson told congressional investigators in a private meeting over the Fourth of July holiday, "and it appears thoroughly to us that the department is really trying to figure out a way to push the information away from their political appointees at the department."

Not only was the department slow to react, Melson said, but Justice Department officials indicated they did not want him to cooperate with Congress.

A transcript of his comments was released Monday by Rep. Darrell Issa (R-Vista), chairman of the House Committee on Oversight and Government Reform, and Sen. Charles E. Grassley of Iowa, the top Republican on the Senate Judiciary Committee.

Melson said he wasn't attempting to shield his agency from its share of the blame. He acknowledged an instance in which his agents failed to intercept high-powered weapons when they could have.

"The deputy attorney general's office wasn't very happy with us" at the ATF, Melson said, "because they thought this was an admission that there were mistakes made. Well, there were some mistakes made."

Justice Department officials denied they were stonewalling the congressional investigation. They said they were cooperating and had been providing thousands of pages of documents and other material to investigators.

"Any notion that the department has failed to cooperate with the investigation is simply not based in fact," said Tracy Schmaler, a Justice Department spokeswoman. She added that the department's inspector general's office was reviewing the Fast and Furious operation.

"The department, like the committee, is interested in determining whether Operation Fast and Furious was appropriately handled," Schmaler said.

The intent of Fast and Furious was to allow illegal straw purchasers to buy guns so ATF agents could follow the weapons and ferret out gun-smuggling routes into Mexico. But many of the approximately 1,700 weapons eluded tracing — some even before they were shipped over the border.

Nearly 200 of the weapons were later found at crime scenes in Mexico, and two were recovered at the scene of a U.S. Border Patrol agent's slaying in Arizona in December.

Melson said the Justice Department repeatedly thwarted his attempts to tell investigators about the failures of Fast and Furious, which was run out of the ATF's Phoenix field office. When the ATF reassigned managers in Phoenix, he said, "the department resisted" his offer to tell Congress about the changes. Melson said he was told not to issue any news releases about Fast and Furious and was instructed not to brief rank-and-file ATF agents about the growing scandal.

When Grassley sought to meet with Melson this year, the Justice Department blocked that interview too, Melson said. "This is really just poking [Grassley] in the eye," Melson said he told Justice Department officials. "He's going to get it through the back door anyway, so why are we aggravating this situation?"

Melson said he felt "very torn" when he learned after the operation went awry that some of the Mexican drug cartel leaders targeted in the program were paid informants for the FBI.

"Let me say that I am frustrated and disappointed in the way the whole thing has been handled, unfortunately," he said.